1. Field of the Invention
The invention relates to a device for bark-peeling (debarking) tree trunks and the like, and in particular to such a debarking device which has a rotating bark-peeling tool that comprises a knife roller provided with skinning knives and which is mounted on a pivot arm so as to be displaceable or pivotable towards the tree trunk, the tree trunk from which the bark is to be peeled being displaceable relative to the bark-peeling tool in the direction of its longitudinal axis with the aid of wheels guided on rails and which is rotated about its axis by means of a driving apparatus.
2. The Prior Art
The peeling of bark from tree trunks and large branches is still frequently performed even at present by arduous manual labour. The main reason for this would appear to be that no sufficiently simple and transportable machine is available which will permit bark removal in situ, i.e. immediately following felling in the forest. Conveying the trunks to the fixed bark-removal plants is awkward and expensive. In addition, for reasons of space, many fixed bark-removal plants can only work with tree trunks of limited length.
Various devices for bark-peeling tree trunks are already known in which a rotating knife roller which is provided with skinning knives is mounted on a pivot arm--see U.S. Pat. Nos. 1,986,708 and 3,416,581, as well as French Pat. No. 1,125,189. The tree trunk from which the bark is to be peeled is moved past the knife roller and is rotated about its axis. In the case of the known devices the knife roller is mounted on the pivot arm in such a way that its axis of rotation extends either in the longitudinal direction of the tree trunk or at a right angle thereto. The tree trunk itself is supported on rollers which are driven in a revolving manner in order to rotate the tree trunk. With these known devices only tree trunks which have grown relatively straight may have their bark peeled, since, in the case of tree trunks with a pronouncedly non-circular cross-section or with an axis extending in a curve, the pivot arm supporting the knife roller must make excessive pivoting movements on account of the rotational movements of the tree trunk, so as to permit satisfactory treatment. In addition, the known drives are relatively complicated, so that they are suitable practically only for stationary operation.
Furthermore, it is known, in the case of machines for processing tree trunks, to arrange the skinning knives in single- or multiple-thread helices on the surface of the knife roller. In a known design (German Published Specification No. 2,712,985), skinning bands, which are supplemented by knife bands extending on the surface of the roller in the axial direction, are arranged on a holding means which extends helically. In a similar known design (see German Pat. No. 961,208) the helical skinning knives have a complicated profile, which consists of radial cutters, a comb surface, a cutting edge and a groove. There, too, the axis of rotation of the knife roller extends axially parallel to the tree trunks to be processed. In addition, the skinning knives used are complicated and quickly wear out, so that they must be re-ground. In some designs some depth-limiting means are required in order to prevent excessively deep penetration of the skinning knives into the tree trunk.